U.S. Pat. No. 6,335,345 (issued Jan. 1, 2002) discloses the compound of structural formula I.

Compound I, and its novel polymorphic forms, are NPY5 antagonists useful as agents for the treatment of various diseases related to NPY, including, but not limited to, cardiovascular disorders, such as hypertension, nephropathy, heart disease, vasospasm, arteriosclerosis, central nervous system disorders, such as bulimia, depression, anxiety, seizure, epilepsy, dementia, pain, alcoholism, drug withdrawal, metabolic diseases such as obesity, diabetes, hormone abnormality, hypercholesterolemia, hyperlipidemia, hypertension, metabolic syndrome, sexual and reproductive dysfunction, gastrointestinal disorder, respiratory disorder, inflammation and glaucoma.
A novel process for the preparation of Compound I was disclosed in WO 01/14376 (published 1 Mar. 2001). The disclosed coupling process employed EDC-HCl and required the separate free base formation step of the pyrazole salt prior to use. Safety and cost concerns associated with the EDC-HCl route led to the development of the present route, which uses thionyl chloride as an improved reagent for the transformation and in which the free base step is performed in-situ. The yield of the improved streamlined process is comparable to the original process.
The original process for the preparation of Compound I, as disclosed in WO 01/14376, yielded Compound I as a mixture of crystalline Form A and amorphous compound. However, the instability of Form A at room temperature complicated the development of solid dosage formulations for compound I. It is therefore desirable to have available other crystalline forms of Compound I having improved stability for the preparation of a solid pharmaceutical dosage form containing Compound I as the active pharmaceutical ingredient. There is no specific disclosure or discussion of pure crystalline Form A, crystalline Form C or the crystalline mesylate and fumarate salts of compound I in U.S. Pat. No. 6,335,345 or WO 01/14376.